The money was up $8000 from the 2018 sale, and close to the record $20,000 set 12 years ago.
Principal Daniel Murfitt said thousands of people had turned up, both to support the school and to grab a bargain book over the weekend.
He said it was neat to see children curled up in the hallways, reading next to their piles of books.
"All in all it's been a hugely successful weekend."
How the money is spent is down to the school's parents' association.
"In the past they've put money towards school vans, scholarships, chairs for the hall, towards science equipment, all sorts of things.
"One of the parents' association's big goals is to promote the college as a centre of educational excellence.
"They organise speakers to come in and invite anyone from the community to come and enjoy a stimulating talk as well as free coffee and cake.
"On July 17 we've got the chief of the Navy, Rear Admiral David Proctor, who is a former Colenso head boy, here to speak and on September 11 we've got IronMaori founder Heather Skipworth coming in."
He wanted to thank Clarke for all her hard work over the years.
"She's doing all the background work."
"And then there's a core group of ex-parents association people who help, people who have supported the sale for 30 years who turn up on the day and help.
"In July we're hosting an event to thank all the people who have volunteered over the years.
"We're in touch with many but are keen to hear from former volunteers so we can invite them to the thank-you function. Just phone the school. We'd love to see them all."